POS1198-HPR PREVALENCE OF INFLAMMATORY BACK PAIN IN PRIMARY SJOGREN’S SYNDROME IS INCREASED AND ASSOCIATED WITH ACUTE AND STRUCTURAL CHANGES OF THE SACROILIAC JOINT
Authors: K. Abacar, Ş. Çolakoğlu Özkaya, E. Biyikli, O. Buğdayci, P. Atagündüz, Z. D. Selcuk
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> An increased prevalence of axial articular manifestations has recently been reported in primary Sjögren's syndrome (pSS).<sup>[1]</sup>Radiologic findings associated with inflammatory back pain (IBP) are not well documented in pSS patients. <h3>Objectives</h3> To assess the prevalence of IBP and its association with magnetic resonance imaging (MRI) detected acute inflammatory and structural changes of sacroiliitis in pSS patients with IBP. <h3>Methods</h3> In this cross-sectional study, consecutive pSS patients fulfilling ACR/EULAR classification criteria and age- and sex-matched healthy controls (HC) were screened for IBP according to the Calin, Rudwaleit and ASAS IBP criteria.<sup>[2]</sup> Sacroiliac MRI imaging of patients with IBP was performed and SpA features in the ASAS Classification Criteria for Axial Spondyloarthritis (SpA) were questioned. Two radiologists assessed sacroiliac joint MRIs (SIJ/MRI) for the cut-off values for a possible diagnosis of axSpA using ASAS defined lesion definitions. Cut-off values were defined previously by Maksymowych et al.<sup>[3]</sup>. The First questionnaire was used to evaluate the relationship between fibromyalgia and back pain.<sup>[4]</sup> <h3>Results</h3> A total of 202 pSS patients meeting the ACR/EULAR classification criteria and 124 healthy controls were included. The mean age [mean (SD)=52.8 (11.9)] and sex distribution in pSS (female/male: 198/4) was similar to HC [51.5 (9.2), (p=0.3) and female/male: 119/122? 5, (p=1), respectively] IBP was more prevalent in pSS (for pSS n(%): 51 (25.2), for HC n(%): 11 (8.8), p&lt;0.001). SIJ/MRI was available in 49 patients with IBP. The mean (SD) age of onset of IBP was 33.6 (5.8). The mean (SD) duration of the IBP of the patients with pSS was 18.9 (10) years. pSS patients with IBP had significantly higher scores of the First questionnaire (patients with IBP mean (SD): 3.9 (1.7), patients without IBP: 2.8 (1.9), p=0.001). A total of 12 (24.5%) patients could meet the an axSpA diagnosis with a PPV of ≥95% as defined by Maxymowych et al. <sup>[3]</sup> Of these 12 patients, two with edema in the sacroiliac joint, nine with erosions, and four with fat metaplasia could be diagnosed as axSpA based solely on SIJ/MRI findings. <h3>Conclusion</h3> Low back pain meeting the IBP criteria is highly prevalent in pSS, and a quarter of these patients may have a radiologic diagnosis of axSpA. However, axSpA-associated features are absent in most patients, and very few meet the ASAS classification for axSpA. The presence of increased fibromyalgia may lead to an over-interpretation of radiologic features in the majority of these patients. <h3>References</h3> [1] Jarrot PA et al J Rheumatol 2021 [2] Hamilton L. et al Rheumatology (Oxford) 2014 [3] Maksymowych WP et al J Rheumatol 2021 [4] de Sousa AP et al. Adv Rheumatol. 2022 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.